Thermal stability, electrical conductivity and ammonia sensing studies on p-toluenesulfonic acid doped polyaniline:titanium dioxide (pTSA/Pani:TiO2) nanocomposites

Electrically conductive p-toluenesulfonic acid (pTSA) doped polyaniline (Pani):titanium dioxide (TiO2) nanocomposites (pTSA/Pani:TiO2) were prepared by in situ polymerization of aniline with TiO2 nanoparticles. Thus formed pTSA/Pani:TiO2 nanocomposites were characterized by Fourier transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The sensitivity of the nanocomposites towards low concentrations of aqueous ammonia was examined and compared with that of the pure Pani. It was found that the resistivity of pTSA doped nanocomposites increases on exposure to ammonia at room temperature. The nanocomposites were found to possess superior ammonia sensing capacity as compared to pure Pani and it showed linear relationship between the responses and the ammonia concentration. The Fourier transform infrared (FTIR) spectroscopy was used to explain the sensing mechanism. A novel mechanism for the interaction process between the sensing material and ammonia has also been proposed.